.TH SG_PREVENT "8" "November 2012" "sg3_utils\-1.35" SG3_UTILS
.SH NAME
sg_prevent \- send SCSI PREVENT ALLOW MEDIUM REMOVAL command
.SH SYNOPSIS
.B sg_prevent
[\fI\-\-allow\fR] [\fI\-\-help\fR] [\fI\-\-prevent=PC\fR]
[\fI\-\-verbose\fR] [\fI\-\-version\fR] \fIDEVICE\fR
.SH DESCRIPTION
.\" Add any additional description here
Sends a SCSI PREVENT ALLOW MEDIUM REMOVAL command to \fIDEVICE\fR.
The default action of this utility is to prevent the removing or
ejecting of the medium from a drive. This is done by ignoring the
SCSI START STOP UNIT command (see sg_start) and ignoring the eject
button on the drive when the user presses it. Drives that hold removable
disks, tape cartridges or cd/dvd media typically implement this command.
The definition of the "prevent" codes for this command differ between
disks and tapes (covered by SBC\-3 and SSC\-3) and cd/dvd drives (covered
by MMC\-5). The "prevent codes" described here are from MMC\-5.
.SH OPTIONS
Arguments to long options are mandatory for short options as well.
.TP
\fB\-a\fR, \fB\-\-allow\fR
allow medium removal. This is equivalent to setting to '\-\-prevent=2'.
Cannot be used with \fI\-\-prevent=PC\fR option (i.e. either use
no options (hence prevent removal), this option or \fI\-\-prevent=PC\fR).
.TP
\fB\-h\fR, \fB\-\-help\fR
output the usage message then exit.
.TP
\fB\-p\fR, \fB\-\-prevent\fR=\fIPC\fR
where \fIPC\fR is a prevent code value. Defined values are: 0 allows removal,
1 prevents removal (default), 2 allows persistent removal while 3 prevents
persistent removal. "Persistent" in this context means that the
initiator (port) that successfully uses code 3 blocks other initiators (ports)
from allowing removal. A "persistent prevent" state can be cleared by the
owner allowing persistent removal (code 2) or a power cycle (or anything that
resets the device (LU)) or some special commands (e.g. various service
actions of Persistent Reserve Out, see SPC\-3).
.TP
\fB\-v\fR, \fB\-\-verbose\fR
increase the level of verbosity, (i.e. debug output).
.TP
\fB\-V\fR, \fB\-\-version\fR
print the version string and then exit.
.SH EXIT STATUS
The exit status of sg_prevent is 0 when it is successful. Otherwise see
the sg3_utils(8) man page.
.SH AUTHORS
Written by Douglas Gilbert.
.SH "REPORTING BUGS"
Report bugs to <dgilbert at interlog dot com>.
.SH COPYRIGHT
Copyright \(co 2004\-2012 Douglas Gilbert
.br
This software is distributed under a BSD\-2\-Clause license. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
.SH "SEE ALSO"
.B sg_start(sg3_utils), sg_persist(sg3_utils)
